CALAMOCRTNUS DIOMED.E. 67 



Einbrvology of Echinodoriiis, both published in 1864, though lie quotes 

 the title of the last memoir; for he makes no allusion to my description 

 of the central anal plate in young- Echinoids in 1864, except in connection 

 with my paper on the young stages of Sea-urchins in the Preliminary Re- 

 port on the Echini dredged by Mr. Pourtales* between Florida and Cuba. 

 Nor does Loven, while discussing the homologies of the dorsal plates of 

 several young stages of Asterias glacialis, refer in any way to the descrip- 

 tions and figures given in the " Embryology of the Starfish " of the early 

 stasos of Asteracanthion. 



In 1872 Beyricli t concludes an article on the basis of the Crinoidea 

 brachiata with suggestions on the analogies of the peculiar subdivision of 

 the basis of the Crinoids and the symmetrical structure of other Echi- 

 noderms, especially Sea-urchins. He says the radials and interradials of 

 Crinoids correspond to the ambulacra and interambulacra of the Sea- 

 urchins, and, further, that the radials of Sea-urchins, as in the Crinoids, do 

 not unite at the dorsal pole, but are separated by the apical system (Schei- 

 telapparat), which from its position is analogous to the basis of the Crinoids. 

 He also calls attention to the fact that in the symmetrical Sea-urchins one 

 of the interradials is specialized above the others by the presence of the 

 anus, dividing the test sjmimetricall}' by an anal axis, as in the Crinoids. 

 He also says that in the composition of the apical system of the Sea-urchins 

 we find no analogue to the deviation of the regular pentagonal subdivision 

 of the basis of the Crinoids. 



Miiller in 1854 also already foreshadows the apical homologies of the 

 Echinoderms. He says: " Der Kelch eines . . . Echinosphjerites, Echinoen- 

 crinus sei der Apex eines Seeigels, er ist jedoch eine solche Ausdehnung 

 des Apex, welche die saramtlichen Eingeweide des Thiers umfasst." :{: 



In the comparison which I made between the plates of the young Star- 

 fish and those of a Crinoid, I spoke of the central plate as present in both, 

 and called attention to the absence of homology between plates which 

 constitute the bulk of the- apical system in the young stages of the Star- 

 fish and Crinoid, homologizing the genitals of the young Starfish (the 

 interradials,§ as I called them) with the basals of Allman's Antedon stage. 



* Bull. Mus. Comp. Zobl., Vol. I. No. 9, 1869. 



t Monatsber. d. K. Akad. d. Wiss. Berlin, Feb. 9, 1871, p. 54. 



t Miiller, Bail der Echinodermen, 1851, p. 14. 



§ But I had no intention of comparing them to what have been called interradials or calyx inter- 

 radials iu palteozoic Crinoids. I merely intended to state that they were plates having an interradial 

 position. 



